According to the Office of the Historian, the Department of State established the Executive Secretariat in Mar 1947 to regulate the flow of information within the highest levels of the Department. Its functions have included such various assignments as Protocol (prior to 1955), management of the Department's Operation Center (since 1962) and preparation of briefing papers about the Department during the transitions between Presidential administrations.
The Operations Center (S/ES-O) as you may already know is the Secretary of State's and the Department's communications and crisis management center. Working 24 hours a day, the Ops Center monitors world events, prepares briefings for the Secretary and other Department principals, and facilitates communication between the Department and the rest of the world. The Operations Center also coordinates the Department's response to crises and supports task forces, monitoring groups, and other crisis-related activities.
Since the Secretary is marking the 50th anniversary of the Ops Center, she must have better information than the Historian's Office. Or it could be that the Ops Center was created in 1961 but its management was not placed under the Executive Secretariat until 1962.
Below is part of Secretary Clinton's remarks on the 50th anniversary of the Ops Center:
Now, thanks to the Ops Center, we can stay connected, and it certainly is a lot easier today than it was in 1961. And many of us have stories. I just want to mention one or two that really have impressed on me what we are dealing with when we give an assignment to the Ops Center.
Now, one evening, I wanted to speak with an ambassador who was visiting Washington, so of course, I asked Ops to find him for me. And a few minutes later, the phone rang, and it was the ambassador on the line, and Ops patched me through. It was to me just sort of matter of fact, simple exchange. Only later I learned that the ambassador did not have his cell phone with him. So Ops called a member of his staff, who said that the ambassador was out to dinner, but he didn’t know where. Ops called the ambassador’s hotel and learned that the concierge had recommended three restaurants – (laughter) – but they didn’t know which one he chose. So Ops called them all, sent a picture of the ambassador, asked them to scan their dining rooms until he was found. And all of this happened in a matter of minutes, and I didn’t know anymore than the fact that I’d asked for and received the connection that I was looking for. That is perseverance. (Laughter.)
Another one of my favorite stories happened just this past March. Some of you might remember that in the very early days of the action over Libya, we had a plane go down, and we had two pilots who had, unfortunately, had to bail out of those planes. One of those pilots in the Libyan Desert was found by a man who had once received an educational grant from the State Department. Members of Congress, I hope you are listening. (Laughter.) So this Libyan gentleman didn’t know what to do with this American pilot that he had literally stumbled upon. So what did he do? He called Ops. (Laughter.) (Applause.) And what did Ops do? Well, Ops called the Defense Department – (laughter) – and said, “Oh, by the way, we have your pilot. Why don’t you come pick him up?” (Laughter.)
And when the earthquake struck Haiti, people called Ops not only from all over the world, but from damaged buildings inside Port-au-Prince, and Ops helped to organize their rescue.
And as we’ve already heard about Pat Kennedy, our absolutely inveterate responder to any bad weather anywhere, when Cheryl Mills was traveling back from Haiti in the middle of what turned out to be that huge snowstorm last year and had to be in the office for our follow-up work on what we were doing regarding Haiti, her plane was first diverted to New York, then she had to get on a train that was still running to Washington. And I think she might have thought, “Okay, fine, if I can just get to Washington, I’ll be lucky. I can get to the office.” But of course, there was no transportation; everything had been shutdown except for Ops. So Ops sent people with shovels and coffee and a 4-wheel drive – I think driven by Pat Kennedy – (laughter) – to pick her up at Union Station.
Now, we know, too, that as the work of the State Department goes on, there’s always something happening somewhere in the world. And sometimes it’s not as dramatic as rescuing – helping to rescue a downed American pilot, but it’s just as important to the people who are involved in very difficult circumstances. So we were working feverishly to evacuate United States citizens from Tripoli and all of Libya, but particularly our Embassy family and those Americans who were in Tripoli, and we hired a ferry to bring them all out. And the ferry made it from Malta to Tripoli.
We worked tirelessly to get permission from the Libyan officials to make sure we could get our people picked up, and then the ferry sat in the harbor for three days. The weather was terrible, the seas were high. And what did Ops do? Well, they supplied the ferry captain with up-to-the-date weather reports from the Navy, they comforted the families by saying that, “We’ll stay on this line with you as long as it takes.” They set up a conference call for me so that I could talk to our people who were on the ferry. And when the ferry finally arrived in Malta, I was in the Situation Room waiting to hear that the ferry had arrived so that we then could take much more vigorous public action against the Qadhafi regime. And Ops sent me the news and then sent out a news alert worldwide.
Now, the 60 men and women who work at the Ops Center are among the most talented Foreign Service – civil service officers that we have. We know that the jobs can be grinding. We know that it’s rare that we have an occasion like this with television cameras who are here to celebrate what you do every day, and you don’t ask for this kind of attention, but you really do make the State Department run.
And so I am delighted to say thank you. I want to thank you for your supreme professionalism, your cool-headedness, your resourcefulness, and above all, your commitment to help absolutely anyone who calls your number. Because when the phone rings at Ops, whatever time it is, somebody is there. And somebody is there not just to answer the phone and then fob them off to another day or another person, but to really understand what needs to be done. And that makes it possible for us to do our work here.
And it’s very exciting for us to have two of our esteemed secretaries of state here with us. And I think that Secretary Eagleburger actually was there at the creation – (laughter) – and so I think we should invite him to the podium, followed by Secretary Albright, who just wore out Ops – (laughter) – during her time. And I hear some knowing laughter, because I know she made phone calls than probably her ten predecessors and successors did. But please join me in welcoming first Secretary Eagleburger and then Secretary Albright. (Applause.)
Full remarks posted here.
(must-read chapters #9 on Bases and #10 on Visitors to Manila): 
by David Warwick from Harvard Press (1975). There is also Managing Diplomacy (1984) where career diplomat, Harrison M. Holland writes about it at length (see pages 172-187). The surprising thing is how the organization has both changed and remained the same in so many ways. The most recent book about the service is 
by former Foreign Service officer, Harry Kopp and the late Ambassador Charles Gillespie (former ambassador to Grenada, Colombia and Chile). The last one is a good read, although it does not go deep enough on the internal life of the organization:
